School of Dentistry and Stomatology, Université catholique de Louvain, Brussels, Belgium.
Dent Mater. 2011 Feb;27(2):157-64. doi: 10.1016/j.dental.2010.09.011. Epub 2010 Nov 9.
To test the influence of photoinitiator type and filler particle inclusion on the validity of exposure reciprocity law.
50/50 wt% Bis-GMA/TEGDMA resins were prepared with equimolar concentrations of camphorquinone/DMAEMA (0.20/0.80 mass%) (CQ) or Lucirin-TPO (0.42 mass%), and were used either unfilled or filled to 75 mass%. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using four different curing protocols: 400 mW/cm² for 45 s as reference protocol (18 J/cm²), 1500 mW/cm² for 12 s (18 J/cm²), 3000 mW/cm² for 6 s (18 J/cm²) and 3 s (9 J/cm²). Degree of conversion (DC) was measured in real time for 70 s by FT-NIRS and temperature rise using a thermocouple. Depth of cure was determined with a penetrometer technique.
With respect to DC and depth of cure, exposure reciprocity law did not hold for any tested material, except for the depth of cure of filled CQ-based materials. At similar radiant exposure, DC was significantly higher (p<0.05) for all unfilled and filled TPO-based materials compared with CQ-based materials. As exposure time was reduced and irradiance increased, TPO-based materials exhibited higher DC whilst an opposite trend was observed for CQ-based materials (p<0.05). For similar curing regimes, depth of cure of CQ-based materials remained significantly greater than that of TPO-based materials. Adding fillers generally reduced DC, except at higher irradiance for CQ-based materials where a positive effect was observed (p<0.05).
The validity of exposure reciprocity law was dependent on several factors, among which photoinitiator type and filler content were important. Lucirin-TPO is a highly reactive and efficient photoinitiator, which may allow the potential for a reduction in curing time of TPO-based photoactive materials in thin sections.
测试光引发剂类型和填料颗粒包含对曝光互易律有效性的影响。
用等摩尔浓度的樟脑醌/二甲基丙烯酰胺（0.20/0.80 质量%）（CQ）或 Lucirin-TPO（0.42 质量%）制备 50/50wt% Bis-GMA/TEGDMA 树脂，并分别将其未填充或填充至 75wt%。使用卤素瑞士大师灯（EMS，瑞士）采用四种不同的固化方案对样品进行固化：作为参考方案的 400mW/cm² 45s（18J/cm²），1500mW/cm² 12s（18J/cm²），3000mW/cm² 6s（18J/cm²）和 3s（9J/cm²）。通过 FT-NIRS 和热电偶实时测量实时转化率（DC）和温度升高。使用透入度计技术测定固化深度。
就 DC 和固化深度而言，除了填充 CQ 基材料的固化深度外，曝光互易律不适用于任何测试材料。在相似的辐射暴露下，与 CQ 基材料相比，所有未填充和填充 TPO 基材料的 DC 明显更高（p<0.05）。随着曝光时间的减少和辐照度的增加，TPO 基材料表现出更高的 DC，而 CQ 基材料则表现出相反的趋势（p<0.05）。对于相似的固化方案，CQ 基材料的固化深度明显大于 TPO 基材料。一般来说，添加填料会降低 DC，除了 CQ 基材料在更高的辐照度下观察到正向效应（p<0.05）。
曝光互易律的有效性取决于几个因素，其中光引发剂类型和填料含量是重要因素。Lucirin-TPO 是一种高反应性和高效的光引发剂，它可能允许减少 TPO 基光活性材料在薄片中的固化时间。
